In an in-cylinder injection internal combustion engine configured to inject fuel directly into a cylinder, a time from injection to combustion is short in comparison with an intake port injection internal combustion engine configured to inject fuel to an intake port. Hence, a time secured to atomize injected fuel is so short that it is necessary to turn injected fuel to fine particles by increasing an injection pressure to a high pressure. Accordingly, in the in-cylinder injection internal combustion engine, fuel pumped up from a fuel tank using an electric low-pressure pump is supplied to a high-pressure pump driven by power of the internal combustion engine, and high-pressure fuel discharged from the high-pressure pump is pressure-fed to an injector.
Generally, the in-cylinder injection internal combustion engine is provided with a fuel pressure sensor detecting a pressure of fuel (fuel pressure) supplied to the injector. A target fuel pressure is set according to an operating state of the internal combustion engine and a discharge quantity of the high-pressure pump is controlled by feedback in such a manner that an actual fuel pressure detected by the fuel pressure sensor coincides with the target fuel pressure.
In the in-cylinder injection internal combustion engine as above, a discharge quantity of the low-pressure pump is varied according to an operating state of the internal combustion engine as is described in Patent Literature 1. Hence, a discharge quantity of the low-pressure pump is restricted from becoming excessive for fuel consumption (that is, a fuel injection quantity) by varying a discharge quantity of the low-pressure pump in response to fuel consumption that varies with an operating state of the internal combustion engine. Wasteful power consumption by the low-pressure pump is thus restricted.